1. Field of the Invention
The present invention relates to a method for inspecting a honeycomb fired body and a method for manufacturing a honeycomb structured body.
2. Discussion of the Background
In recent years, particulates such as soot contained in exhaust gases that are discharged from internal combustion engines of vehicles, such as buses and trucks, and construction machines, have raised serious problems as contaminants harmful to the environment and the human body.
Various honeycomb filters using honeycomb structured bodies made from porous ceramic materials, which serve as filters that capture particulates in exhaust gases to purify the exhaust gases, have been proposed.
Conventionally, upon manufacturing a honeycomb structured body, first, ceramic powder and a binder are dry-mixed, and to this is further added a dispersant solution, and mixed so that a wet mixture is prepared. Then, the wet mixture is continuously extrusion-molded through a die, and the extruded molded body is cut into a predetermined length so that a pillar-shaped honeycomb molded body is manufactured.
Next, the resulting honeycomb molded body is dried, and predetermined cells are sealed so as to manufacture a honeycomb molded body in which one of ends of each cell is sealed with a plug material layer, and thereafter, a degreasing process and a firing process are carried out on the honeycomb molded body so that a honeycomb fired body is manufactured.
Thereafter, a sealing material paste is applied to the side faces of each of the honeycomb fired bodies, and the honeycomb fired bodies are combined with one another to manufacture an aggregate of the honeycomb fired bodies in which a number of honeycomb fired bodies are combined with one another by interposing sealing material layers (adhesive layers). Next, the resulting aggregate of the honeycomb fired bodies is cut and machined into a predetermined shape such as a cylindrical shape and a cylindroid shape by using a cutting tool or the like to form a ceramic block, and lastly, a sealing material paste is applied onto the outer periphery of the ceramic block to form a sealing material layer (coat layer); thus, a honeycomb structured body is manufactured, and then an inspection is carried out on the honeycomb structured body thus manufactured, thereby completing the manufacturing of the honeycomb structured body.
In the present specification, in any of the forms of the honeycomb molded body, honeycomb fired body and honeycomb structured body, those faces to which cells are exposed, among faces that form the respective external shapes, are referred to as end faces, and those faces other than the end faces are referred to as side faces.
Here, with respect to the inspection method to determine whether or not a honeycomb structured body has a crack, there have been proposed a method for detecting a crack on the surface of a honeycomb structured body in which a temperature gradient is generated in the honeycomb structured body to measure the surface temperature distribution so that a crack is detected by conducting a predetermined image processing on the resulting temperature distribution; and a crack detection method for a honeycomb structured body in which the honeycomb structured body is placed with its end faces facing up and down on a mounting face, and applied thereto an impact load so much as to allow powder matters to drop from a portion having a crack, so that a crack is detected by detecting the dropped powder matters. See, for example, Japanese Unexamined Patent Application Publication No. 2003-207472 and Japanese Unexamined Patent Application Publication No. 2004-45276. The contents of JP-A 2003-207472 and JP-A 2004-45276 are incorporated herein by reference in their entirety.